1. Field of the Invention
The present invention relates to a keyboard apparatus that is used in a keyboard type electronic musical instrument, such as an electronic piano or the like, and a training apparatus to be used by a player in training on the piano and other keyboard type musical instruments.
2. Description of Related Art
Typical keyboard apparatuses for keyboard type musical instruments are described in Japanese Laid-open Utility Model Application SHO 56-99596, Japanese Laid-open Patent Application HEI 4-107296 (electronic organs, etc.), Japanese Utility Model Patent HEI 5-954 (electronic pianos, etc.), and Japanese Utility Model Patent HEI 5-22956 (acoustic pianos, etc.).
The keyboard apparatuses described in these references normally have a keyboard including a supporting member and a plurality of white keys and black keys (generally referred to as keys) mounted on the supporting member. Each of the plurality of keys is pivotally mounted about its fulcrum with respect to a supporting member and a driving section (an actuator section). When a key is depressed, the driving section drives a movable section such as a key switch, an action member including a hammer, a whipping (or whippen) assembly, a valve and the like. The actuator section (the driving section) is typically separated a specified distance from the fulcrum of the key.
Nowadays, electronic musical instruments are capable of generating musical sounds that are quite similar to those generated by an acoustic piano. In this connection, there are demands that keyboard apparatuses provide a key touch feeling comparable to the key touch feeling that is provided by a keyboard apparatus of an acoustic grand piano.
The above-mentioned Japanese Utility Model Patent HEI 5-954 teaches a keyboard apparatus for electronic musical instruments which meets such key touch feeling demands. Japanese Utility Model Patent HEI 5-954 shows a keyboard frame and a plurality of keys mounted on the keyboard frame. Each of the keys is pivotable with respect to the keyboard frame. A mass body (a hammer) is pivotally and movably supported at a mass body supporting section provided at each of the keys or on the keyboard frame and is movable in association with each of the keys upon depression or release of the associated key. The mass of the mass body is relatively concentrated at a tip portion of the hammer and is used to generate a moment of inertia that provides a key touch feeling similar to the key touch feeling provided by an acoustic piano.
It is appreciated that when a player depresses white keys and black keys with a finger, the distance between the finger of the player and the fulcrum of the white key is generally different from the distance between the finger and the fulcrum of the black key. In consideration of the difference in the lever ratios and to provide the same counter force that is received by the finger, in other words, to provide the same key touch feeling, the masses are provided in different sizes for the white keys and the black keys. More particularly, the mass of a hammer for the black key is smaller than the mass of a hammer for the white key. Furthermore, the white keys are designed to abut against their associated hammers at a position different from a position where the black keys abut against their associated hammers.
As described above, in the conventional keyboard apparatuses having masses such as hammers, mass bodies for the white keys are manufactured independently from mass bodies for the black keys as different parts. As a result, metal molds for forming the hammers for the white keys are prepared independently from metal molds for forming the hammers for the black keys. Consequently, the cost for manufacturing and maintaining the metal molds increases, and the keyboard apparatus becomes very expensive.
Typically, a split metal mold, that can be split into 4 to 8 metal mold blocks, is often used to form a single part to avoid under-cut and facilitate the molding process. Therefore, when this type of split metal molds are used to make the hammers for the black keys and the white keys, each two of the metal mold blocks for the black keys and the white keys have to be prepared, which is not economical.
The key touch feeling provided by a keyboard apparatus of an acoustic grand piano has the following functional characteristics.
1 The static key touch feeling does not change very much with respect to a key depression stroke. 2 A weak key touch provides a released, advancing feeling (a static let-off feeling). 3 A strong key touch provides a dynamic key touch feeling (a feeling of mass) and a mass released feeling (a dynamic let-off feeling). ( A white key and a black key provide the same key touch feeling.
The functions of 1 and 4 may be achieved by the above-described conventional keyboard apparatus having the mass bodies that move in association with the keys. However, the functions of 2 and 3 are achieved by the let-off function, the back checking function, the repetition function and the like (these functions will be described later in detail) provided by a complex action mechanism of an acoustic grand piano, and cannot possibly be achieved by providing only mass bodies such as simple hammers.
In this connection, an action member may be formed from a plurality of members including a mass body, that are moved in association with an associated key to provide functions similar to the functions of 2 and 3. However, the component members of the action member have to be made in different sizes and different weights for the white keys and the black keys so that the white keys and the black keys will provide the same key touch feeling. As a result, the number of the component members and the number of molds for forming these component members increases, and the overall cost for the keyboard apparatus becomes substantially higher.